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1、數(shù)字信號(hào)處理大作業(yè)電子工程學(xué)院M2.2ThesquarewaveandthesawtoothwavearetwoperiodicsequenceassketchedinFigureP2.1.UsingthefunctionssawtoothandsquarewriteaMATLABprogramtogeneratetheabovetwosequencesandplotthemandtheperiodN.Forthesquarewavesequenceanadditionaluser-specifiedparame
2、teristhedutycycle,whileisthepercentoftheperiodforwhichthesignalispositive.Usingthisprogramgeneratethefirst100samplesofeachoftheabovesequenceswithasamplingrateof20khz,apeakvalueof7,aperiodof13andadutycycleof60%forthesquarewave.如下為matlab程序代碼：%getuserinputsa=inp
3、ut('thepeakvalue=');l=input('lengthofsequence=');n=input('theperiodofsequence');ft=input('thedesiredsamplingfrequency=');dc=input('thesquarewavedutycycle=');%creatsingalst=1/ft;t=0:l-1;x=a*sawtooth(2*pi*t/n);y=a*square(2*pi*(t/n),dc);%poltsubplot(211)stem(t,x
4、)ylabel('Amplitude');xlabel(['Timein',num2str(t),'sec']);subplot(212)stem(t,y);ylabel('Amplitude');xlabel(['Timein',num2str(t),'sec']);在仿真之前，分析題目中所給出的數(shù)據(jù)，需要注意此時(shí)的周期為序列的個(gè)數(shù)13，而非時(shí)間周期13s，否則100個(gè)取樣最終時(shí)間才花費(fèi)0.05s，在圖中就無(wú)法顯示出來(lái)。同時(shí)占空比很明確的影響方波的取樣正負(fù)所占比例，這也與占空比所本意相吻合。周期的多少也直接影響
5、一個(gè)周期內(nèi)取樣的個(gè)數(shù)。M2.4(a)WriteaMatlabprogramtogenerateasinusoidalsequencex[n]=Acos(ω0n+φ）andplotthesequenceusingthestemfunction.TheinputdataspecifiedbytheuserarethedesiredlengthL,amplitudeA,theangularfrequencyω0,andthephaseφwhere0<ω0<πand0≤φ≤2π.Usingtheprogramgenera
6、tethesinusoidalsequenceshowninfigure2.15.(b)Generatesinusoidalsequenceswiththeangularfrequenciesgiveninproblem2.2.Determinetheperiodofeachsequencefromtheplotandverifytheresulttheoretically.Answer:如下為matlab代碼：>>L=input('Desiredlength=');A=input('Amplitude=');o
7、mega=input('Angularfrequency=');phi=input('Phase=');n=0:L-1;x=A*cos(omega*n+phi);stem(n,x);xlabel('Timeindex');ylabel('Amplitude');title(['omega_{o}=',num2str(omega)]);%%example：Desiredlength=100Amplitude=1.5Angularfrequency=0.1*piPhase=0ω0=0.1πω0=0.14π由理論計(jì)算
8、可知其周期t=2pi/0.14pi=100/7，故時(shí)間周期T=100，由圖中也可明顯看出，其波形以100開(kāi)始循壞，故其周期也為100，相符。.ω0=0.24π理論計(jì)算t=2pi/0.24pi=25/3，故其周期為25，由圖中也可看出，其圖像每25一循壞，周期為25，與理論也相符。w0=0.34pi理論計(jì)算t=2pi/0.34pi=100/17，故其周期為100，由圖中，基
